Abstract

Constant rate of strain (CRS) consolidation experiments and flow-through permeability experiments are used to characterize the flow behavior of hemipelagic mudstones at Integrated Ocean Drilling Program Sites C0011 and C0012. Flow-through permeability experiments on samples from Site C0011 (366.76–687.15 meters below seafloor [mbsf]) provide estimates of vertical permeability (kv) that range from 7.03 × 10–17 to 1.38 × 10–18 m2. Flow-through experiments on samples from Site C0012 (273.51–473.11 mbsf) provide estimates of in situ kv from 6.09 × 10–19 to 2.86 × 10–19 m2 and in situ horizontal permeability (kh) of 6.54 × 10–19 m2. At Site C0012 (115.44–255.31 mbsf), CRS-based estimates of in situ kv range from 1.12 × 10–17 to 2.54 × 10–18 m2 and in situ kh ranges from 1.66 × 10–17 to 6.55 × 10–18 m2. For the four depths at Site C0012 where vertical and horizontal permeability calculations were made, the permeability ratio (kv/kh) ranges from 0.38 to 0.99. Where calculated, kv/kh does not show any depth trends.

Neglecting one anomalous data point, all data show permeability decreases with increasing depth and decreasing porosity. Flow-through data document greater permeability at Site C0011 compared to Site C0012 at equivalent depths below 350 mbsf. In lithologic Units III and IV, permeability estimated by flow-through experiments at Site C0011 is greater than at Site C0012. Drilling and coring disturbance exists in all samples and adjacent shipboard samples, suggesting that all permeability estimates have been impacted by sample disturbance, should be viewed with caution, and should be considered an upper limit on in situ permeability.